1. Field of the Invention
The present invention relates to a semiconductor device for use in, e.g., optical disc drives, displays, and optical communications, etc.
2. Background Art
Japanese Laid-Open Patent Publication No. S60-92686 discloses a semiconductor device in which a semiconductor laser element is mounted on a submount. This submount is formed of an alloy of W and Cu, an alloy of Mo and Cu, or an alloy of W, Mo, and Cu. The coefficient of thermal expansion of the submount is substantially equal to that of the semiconductor laser element, which is formed of InP, etc.
It is desirable that a submount does not cause excessive stress on the semiconductor element mounted thereon even at high temperatures and, furthermore, that it has good thermal conductivity. This means that the submount must be formed of a material having a coefficient of thermal expansion close to that of the semiconductor element and having a high thermal conductivity. The submount disclosed in the above publication is formed of such a material. However, the material of this submount is composed of rare metal such as W or Mo, resulting in increased cost of the semiconductor device.